Means and method of slotting strip metal

ABSTRACT

A means for and a method of slotting strip metal prior to drawing the edge portions of the metal apart to form a truss or mesh panel, which comprises driving the strip in the direction of its longitudinal axis past a series of co-axial slotting rollers and simultaneously driving those rollers to cause projections thereon to shear slugs from the strip so as to form slots therein, the simultaneous driving of the strip and driving of the slotting rollers achieving a cut having a smooth surface which reduces stress concentration in the metal as it is expanded.

United States Patent 1191 Jury et al.

[ 1 MEANS AND METHOD OF SLO'ITING STRIP METAL [751 Inventors: Harold Rex Jury, Norwood; Ronald McKenzie Howells, Yennora, both of Australia [73] Assignee: Comalco (J. & S.) Pty., Ltd., New

South Wales, Australia 22 Filed: July 13, 1973 21 Appl. No.: 378,833

[30] Foreign Application Priority Data July 17, 1972 Australia 9721/72 [52] US. Cl. 835/157; 83/311; 83/332; 83/678 [5 1] Int. Cl. 326d 3/00 [58] Field of Search 83/37, 332, 675, 678,311, 83/312 [56] References Cited UNITED STATES PATENTS 671,915 4/1901 Curtis 83/332 845,764 3/1907 Curtis 1 83/332 X [4 1 Sept. 9, 1975 1,441,708 1/1923 Overbury 83/332 2,535,195 12/1950 Colucci, Jr. et a1. 83/678 X 2,808,106 10/1957 Belton H 83/675 X 3,509,788 5/1970 Glendening 83/678 X R1$,328 4/1922 Overbury 83/332 X FOREIGN PATENTS OR APPLICATIONS 1,497,723 9/1967 France 83/332 Primary Examiner.l. M. Meister Attorney, Agent, or Firm-Jay L. Chaskin, Esq.

[57] ABSTRACT A means for and a method of slotting strip metal prior to drawing the edge portions of the metal apart to form a truss or mesh panel, which comprises driving the strip in the direction of its longitudinal axis past a series of co-axial slotting rollers and simultaneously driving those rollers to cause projections thereon to shear slugs from the strip so as to form slots therein, the simultaneous driving of the strip and driving of the slotting rollers achieving a out having a smooth surface which reduces stress concentration in the metal as it is expanded.

16 Claims, 12 Drawing Figures ill-l PATENTED SEP 9 75 sum 1 0F 3 PATENTED 9875 3.903169 sum 3 OF 8 g nur hnuw rb [EE PATENTED SEP 9 I975 SHEET 0F PATENTED SEP 9 i 5 sum '5 0F 3 N mw PATENTED SEP I975 SHEET-10H} MEANS AND METHOD OF SLOTTING STRIP METAL This invention relates to a means for and a method of slotting strip material, and is applicable to but not limited to the slotting of a metal section between flanges prior to the drawing of those flanges apart to form a truss, mesh panel or other metal member.

There is much prior art relating to the formation of expanded metal wherein a sheet of metal is firstly slit with a series of staggered single shear lines, and is subsequently expanded. Thus for example in the US. specification No. 885548 granted to G.A. Turnbull and dated the 21st Apr., 1908 there is described and claimed a metal cutting and forming machine which is useful for the forming of expanded metal by the process of firstly slitting a sheet of metal and then drawing the edges of the sheet apart to thereby form the expanded metal. The said specification constitutes the closest prior art known to the inventor, and incorporates a series of shearing rollers each having a plurality of radial projections extending around it for portions of its circumference.

BACKGROUND OF THE INVENTION In prior art means and methods for the preparation of sheet or strip material for the forming of expanded metal panels, the shear lines have been single shear lines and have ended in sharp edges which cause stress concentration zones at the ends of the slits as the metal is stretched. Thus the metal is useful as a nonloadbearing panel, but is not useful as a loadbearing panel. Furthermore prior art means and methods for the forming of the slits preparatory to expanding a metal sheet which have employed rotary shearing members have included sharp edge tools which func' tion as rotary knives, and for example in the said US. Pat. No. 885548 knife edges are provided on opposite edges of rotary shears so that each knife provides simultaneously two slits in the sheet operated on thereby. The amount of force required to effect slitting of sheet material is very small compared with the amount of force required to effect the formation of slots in strip material of the same thickness. If for example the knives described in the said United States patent were utilised as slotting rollers, then the rollers would not be suitable for transporting the material to be slit through the cutting zone, and the material would be damaged by the roll punches.

OBJECTS OF THE INVENTION The main object of this invention is to provide a means for piercing longitudinally extending slots wherein the strip material in which these slots are to be formed is not seriously damaged by the slotting rollers. A further object is to provide means whereby the slot length can be varied slightly without changing the slotting rollers. A still further object is to provide a means and method whereby slots formed in strip material will have cleanly cut ends which can for example be of arcuate shape, so that development of stress concentration zones is greatly reduced as the material is formed into an expanded metal member. This is of great importance if the overall length of the strip material is not to be reduced as the expansion takes place, and the expansion is accommodated by stretching of the metal between adjacent slots.

BRIEF SUMMARY OF THE INVENTION In this invention a strip material having a constant cross-sectional shape and constituting a workpiece is transported through a cutting zone between back-up means and a plurality of slotting rollers each of which has a radial projection extending around it for part but not all of its circumference, and at the same time the slotting rollers are driven at a speed which is adjusted to be synchronized with the speed of the transporting means which transport the strip past the rollers. By driving the strip through the rollers with transport means, and simultaneously driving the rollers separately and at a carefully adjusted speed, it becomes possible to achieve a very clean cut at the ends of the slots, so that in turn development of stress concentration areas (associated with sharp ended slits or with rough and jagged cuts) is substantially reduced as the strip material is expanded.

More specifically the means of this invention for the forming of longitudinally extending slots in strip material having a constant cross-sectional shape comprise a frame, a pair of aligned bearings carried by the frame, a series of co-axial slotting rollers positioned between the bearings and rotationally supported thereby, each of the slotting rollers having at least one radial projection which extends around it for part but not all of its circumference, back-up means spaced from the rollers but being adjacent thereto so as to define with the rollers a cutting zone, transport means carried by the frame, drive means coupled to the rollers for rotational driving thereof, and further drive means coupled to the transport means for the driving thereof in a direction at right angles to the roller axis, so constructed and arranged that a said strip of material when supported on the back-up means is driven by the transport means through the cutting zone while simultaneously the slotting rollers are driven rotationally, and the projections on the slotting rollers shear slugs from the strip so as to form said slots.

The method of the invention may be defined as a method of forming longitudinally extending slots in strip material having a constant cross-sectional shape, comprising driving the strip in the direction of its longitudinal axis and at right angles to the axis of a series of co-axial slotting rollers and through a cutting zone existing between the rollers and back-up means, each of said slotting rollers having at least one radial projection extending around it for part but not all of its circumference. and simultaneously driving the slotting rollers r0- tationally, thereby causing said projections to shear slugs from the strip material so as to form slots in the strip material.

Conveniently the ends of the projections are curved so that the slots have curved ends, and control means are interposed between the respective drive means of the transport means and of the slotting rollers so that the speeds may be adjusted. If the transport means is adjusted so that it moves the strip workpiece at a higher speed than it would be otherwise moved by the rollers. then the ends of the slot will be found to be cleanly severed with a minimum of drag of material, so that development of stress concentration is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is described hereunder in some detail with reference to and is illustrated in the accompanying drawings in which:

FIG. 1 is a diagrammatic representation illustrating the means for the slotting of strip material, and showing in diagrammatic form the slotting rollers. the back-up means and the transport means,

FIG. 2 is an enlarged cross-section showing the slotting rollers and the back-up means.

FIG. 3 is a fragmentary plan illustrating the machine at the location of the cutting zone,

FIG. 4 is an exploded perspective view which illustrates three elements of a series of slotting rollers. namely a slotting roller, a spacer, and a stripper plate,

FIG. 5 is a longitudinal section through a series of slotting rollers carried on a shaft arranged to be supported between a pair of spindles on the machine,

FIG. 6 is an enlarged section showing the cutting zone and the relationship between the slotted rollers and a back-up roller,

FIG. 7 is an enlarged side elevation of a slotting roller.

FIG. 8 is a half section taken on line 8-8 of FIG. 7,

FIG. 9 is a longitudinal section through a backup roller.

FIG. 10 is a partly diagrammatic view of a hold down roller (when used),

FIG. 11 is a perspective view of an auxiliary table (when used), and

FIG. 12 is a diagrammatic representation showing the control means used for effecting drive to the slotting rollers and to the transport means.

In this embodiment the means for forming longitudinally extending slots comprises a machine having an in-feed roll case 21 and an out-feed roll case 22. Each roll case 21 and 22 is adjustable for height by means of jacks 23 (FIG. 2) each jack 23 having a threaded member 24 which threadably engages a frame 25. In this embodiment only the adjacent ends of the respective roll cases 21 and 22 are adjustable for height, since the amount of adjustment required is relatively small. The other ends are provided with hinge support means (not shown).

The in-feed roll case 21 is provided with a plurality of rollers 28 each carried on a respective shaft 29, the shafts being journalled in bearings 30. The rollers are spaced axially on respective shafts 29, and between the rollers there is positioned a transport chain 31 having dogs 32 thereon. The arrangement is such that a dog 32 engages against an end of a strip workpiece 33 as shown in FIG. 2 for driving the workpiece 33 through a cutting zone designated 34 and which exists between a back-up roller 35 and a series of slotting rollers 36. On the output side of the cutting zone 34 there is also provided a hold down roller 37 which assists in reducing distortion of the workpiece after it has been cut.

The configuration of the slotting rollers 36 is best seen from the drawings of FIGS. 4, 5, 6, 7 and 8. Each slotting roller 36 is provided with a central opening 41 which engages over a shaft 42 and is keyed thereto by means of a key 43. Each roller is also provided with six bolt holes 44 which contain bolts 45, and by this means it is possible to build up a stack of slotting rollers 36. Each slotting roller 36 is provided with a pair of radial projections 46 which are spaced however by recessed portions designated 47. There is at least one radial projection 46, the number being determined by the length and pitch of the slots required in the workpiece strip 33.

Between adjacent rollers 36 are positioned respective spacers 49, and surrounding each spacer 49 is a stripper plate 50, the function of the stripper plate 50 being to assist in avoiding distortion of the workpiece as it is cut, the stripper plates 50 lightly bearing against the upper surfaces of the respective beads on the strip material workpiece 33, which are designated 51 in FIG. 9. Further to assist in avoiding distortion, the outer peripheries of the radial projections 46 are knurled as shown in FIG. 4. This latter feature is an optional feature which in some cases is not used.

The bolts 45 bear against the end plates 53 (FIG. 5), and the end plates themselves are contained between annular packers 54 which surround the shaft 42 and at one end bear against a shoulder 55 and at the other end are retained by means of a spindle nut 56, the ends of the shaft 42 containing respective recesses 58 and 59, in both cases the recesses having tapered walls, and the recess 59 being intersected by a transverse slot 60. In this manner the shaft 42 may be supported between a driven spindle at one end and an idling spindle at the other, while the stripper plates on the shaft 42 constitute a single assembly as shown in FIG. 5, enabling quick change over of tooling if the slot configuration is to be varied. In this respect the tooling is attached to the machine in much the same way as a milling cutter is attached to a milling machine. (The shaft may have projections, and the spindles may be provided with recesses).

FIG. 6 shows the detail of operation of the slotting rollers 36. It will be noted that the axis of the back-up roller 35 was displaced towards the input side of the plane which is normal to the longitudinal axis of the strip workpiece 33. The centre of the cutting zone 34 is essentially upstream" of the said plane, and is designated 66 in FIG. 6. The cutting zone 34 is herein defined as being that portion of the web which is undergoing a shearing action upon rotation of the rollers 36. The pitch cutting speed of each roller is defined herein as the lineal speed of that portion of the roller which is tangential to the mid-plane of the workpiece.

As shown in FIGS. 7 and 8, the ends of the radial projections 46 terminate in radially extending curved surfaces 67, and the side faces of the projections 46 are undercut to provide a rake or cutting clearance 68 as shown in FIG. 8. This reduces drag on the edges of the metal as shearing takes place in the workpiece.

In order to accommodate different cutter diameters, or different heights of beads 51 in different workpieces, it is necessary to be able to adjust the position of the back-up roller 35 in a fore and aft direction, and to this end the back-up roller 35 is carried in bearings (not shown) disposed in bearing blocks 70, and for the same reason the bearings (not shown) in which the shaft 42 is journalled are adjustable vertically, being carried in bearing blocks which are guided for vertical movement by the slides 71. Respective screw members 72 and 73 effect the adjustments.

FIG. 9 illustrates the cross-sectional shape of the back-up roller 35. The back-up roller 35 comprises a plurality of annular members 75 carried on a shaft 76, the shaft 76 being of similar configuration to the shaft 42, again being provided with a shoulder 77 at one end,

a spindle nut 78 at the other, and respective recesses 79 and 80, the recess 79 being intersected by a transverse slot 81. With this arrangement then the assembly which includes the slotting rollers 36 and an assembly which includes the spacers 75 can be manufactured or repaired, and retained as a pair of matched tools.

Not only is it necessary to change the slotting rollers and the back-up roller when a workpiece of different cross-section configuration is to be slotted, but in many instances it is also necessary to reposition the hold down roller 37. This can be effected in any known way, and FIG. illustrates one simple mechanism wherein an air cylinder 84 is coupled to an arm 85 which is pivoted to a standard 86 upstanding from the frame 25, the coupling being effected by means of a bell crank shaped lever 87 and a coupling link 88. The standard 86 is provided with slots 89 which support a block 90 which in turn rotationally support a shaft 91, the shaft 91 having secured to it the bell crank levers 87. Thus the block 90 may be positioned in an upper position for high flanges or beads or in a lower position for low flanges or beads. similarly the slots 93 provide adjustment means for the pin 94 about which the arm 85 piv- OIS.

If it is desired to slot a thin walled workpiece which may be damaged by utilising the back-up roller 35, the workpiece is conveniently positioned on a table designated 96 in FIG. 11, the table 96 having a number of upstanding parallel spaced flanges 97 to support the workpiece between the slotting rollers 36, while the lower or underface of the table is provided with a chain 98 secured thereto and arranged to function as a rack, the chain 98 being identical in size and shape to the transport chain 31. Thus operation of the sprocket 99 which drives the chain 31 will also drive the chain 98 and move the table 96 beneath the slotting rollers 36. In this instance the table 96 becomes the transport means for transporting the workpiece beneath the slotting rollers. The workpiece is retained by means of a stop bar 100 secured to the upper surface of the table 96.

FIG. 12 illustrates diagrammatically the drive means, wherein an electric motor 105 drives a pump 106 which draws oil from a reservoir 107, and drives the oil at pressure through a control valve 108, in turn driving an hydraulic motor 109 which effects drive to the shaft 42 by means of a drive chain 110. The shaft 42 is coupled through a variable ratio drive designated 112 to one of a pair of tacho-generators 113, the tachogenerators controlling a direct current motor 114 through a direct current feed back control module 115 which controls speed of the motor 114 which has the second tacho-generator 113 coupled thereto. The motor 114 drives the back-up roller 35 through a chain drive 116, and drives the sprocket 99 of the transport chain 31 through an electric clutch designated 117 in FIG. 12. In this embodiment the tacho-generators 113 are generators sold under the registered trade mark Morse as an MK series, Morse being a registered trade mark of which Borg Warner International Corporation of Chicago Ill. U.S.A. is a registered user in the Commonwealth of Australia. The tacho-generator item number is SPY, and it is coupled through an MK control designated number MK-2000, driving a horse power motor identified as an MK D.C. motor, part number 2000 DP230, or alternatively 2000 TE 230. All said products are arranged to interface with one another, all are produced by the Borg Warner lnternational Corporation, and all are sold under the registered trade mark Morse.

ln use the machine is operated by firstly inserting a matched pair of tools, namely an assembly including a series of slotting rollers 36 arranged on a shaft 42, and a corresponding series of annular members arranged on a shaft 76. These are arranged to be driven in their respective positions on the machine, respectively by the motors 109 and 114.

The control 115 is adjusted so that the speed of the transport chain 31 (or alternatively of the table 96) is the same as the pitch cutting speed of the rollers 36, or slightly greater. The degree of difference is adjustable by the control 115, and the operator exercises his skill in adjusting the diiference (if any). Slot length and quality of cut can be controlled by varying the speed of the motor 114.

A workpiece is either secured to the table 96 (if this is to be used) or alternatively is positioned over the chain 31 so that its end will be engaged by the dog 32. An impulse is received from a separate sensing means, and this impulse energises the electric clutch 117, the electric clutch 117 being arranged to remain energised until the workpiece has completed its traverse through the cutting zone 34.

In this embodiment the sensing means is a magnet coupled to the shaft 42 and a proximity switch operated thereby. This is not illustrated, and alternative sensing means may be used in lieu thereof. However the sensing switch is fully adjustable to provide means for compensating for starting inertia which varies with workpieces having different weights.

The instant of energising the clutch 117 determines the relationship between the slots and the end of the workpiece. The mechanism for achieving this interlock is in accordance with prior art and forms no part of this invention. After a workpiece has traversed through the machine, the slugs are removed from the machine and the workpiece is removed from the out-feed roll case 22. The workpiece is subsequently expanded by stretching of the metal between the slots which have been formed.

The cross-sectional configuration of the workpiece can vary considerably from that which is shown in FIG. 9, but in all cases it will be seen that beads 51 may be utilised to avoid the need for female dies when slugs are to be removed from the workpiece web so as to form the slots therein.

The above description has been with reference to a machine wherein the slotting rollers are positioned above the workpiece. However the arrangement can be inverted, to have the back-up roller above the workpiece and the slotting rollers beneath it. This arrangement results in ejection of the slugs onto the workpiece, and thereby assists in scrap disposal.

1n the embodiment described, the feed chain and the back-up roller both imparted drive to the workpiece. However, it is not always necessary to utilise both these drives, and either one may be used as the transport means in instances wherein the workpiece does not impart heavy cutting loads on the slotting rollers. However in all cases, both the workpiece and the slotting rollers are driven.

What we claim is:

1. A method of forming longitudinally extending slots in a non-flexible strip material having a constant crosssectional shape, the slotted strip material to be expanded by drawing edges thereof apart, comprising:

driving the strip in the direction of its longitudinal axis and at right angles to the axis of a series of co axial slotting rollers and through a cutting zone existing between the rollers and back-up means, each of said slotting rollers having at least one radial projection extending around it for part but not all of its circumference and terminating in curved surfaces which extend in radial directions,

and simultaneously driving the slotting rollers rotationally to have their pitch cutting speed less than the speed of travel of the strip, thereby causing said projections to shear slugs from the strip material so as to form said slots in the strip material.

2. A method of forming longitudinal slots in strip material according to claim 1 wherein said driving of the strip is effected by engaging one end of the strip with a dog on a transport chain, and driving the transport chain with an electric motor.

3. A method of forming longitudinal slots in strip material according to claim 1 wherein said driving of the strip is effected by securing the strip to a table and driving the table with an electric motor.

4. A method of forming longitudinal slots in strip material according to claim 2 wherein the electric motor is a variable speed direct current motor, and comprising controlling the speed of said motor by means of a tacho generator coupled for drive to the slotting rollers and electrically coupled to said electric motor through a circuit which includes direct current feedback control means.

5. Means for forming longitudinally extending slots in a non-flexible strip material having a constant crosssectional shape, the slotted strip material to be expanded by drawing edges thereof apart, comprising a frame, a series of co-axial slotting rollers rotatably supported by the frame, each of said slotting rollers having at least one radial projection extending around it for part but not all of its circumference and terminating at its ends in curved surfaces which extend in radial directions, back-up means spaced from the rollers but being adjacent thereto so as to define with the rollers a cutting zone, transport means carried by the frame, drive means coupled to the rollers for rotational driving thereof, and further drive means coupled to the transport means for the driving thereof at a speed which exceeds the pitch cutting speed of the rollers,

so constructed and arranged that a said strip of material when supported on the back-up means is driven by the transport means through the cutting zone while simultaneously the slotting rollers are driven rotationally, and said projections shear slugs from the strip so as to form slots.

6. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said frame includes two pairs of upstanding slides, respective said bearings being guided for vertical movement between the slides of said pairs, and threaded members interconnecting the bearings and frame and constituting adjustment means for effecting adjustment of height of the bearings.

7. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said backup means comprise a back-up roller journalled in roller support bearings secured to the frame.

8. Means for forming longitudinally extending slots in strip material according to claim 7 comprising further threaded members coupling the roller support bearings and the frame and constituting position adjustment means for the back-up roller for adjusting the position of the back-up roller in the direction of the longitudinal axis of the strip material.

9. Means for forming longitudinally extending slots in strip material according to claim 7 wherein each of said back-up roller and said series of sliding rollers comprises a shaft, a shoulder at one end of the shaft, a series of annular spacers surrounding the shaft, clamping means clamping the annular spacers against the shoulder, and a tapered recess in each end of each respective said shaft.

10. Means for forming longitudinally extending slots in strip material according to claim 5 further comprising an in-feed roll case carried by the frame and extending in one direction from the cutting zone, and an output roll case extending in the opposite direction therefrom.

1 1. Means for forming longitudinally extending slots in strip material according to claim 10 further comprising height adjustment means between each said roll case and said frame.

12. Means for forming longitudinally extending slots in strip material according to claim 10 further comprising a hold-down roller positioned above the out-feed roll case and adapted to bear against the upper surface of the workpiece at the out-feed side of said cutting zone.

13. Means for forming longitudinally extending slots in strip material according to claim 5 wherein the slots of each said slotting roller radial projection decrease progressively in thickness radially inwardly from the periphery thereof to form a cutting clearance.

14. Means for forming longitudinally extending slots in strip material according to claim 5 further comprising stripper plates between adjacent said slotting rollers, said stripper plates being positioned to bear against a surface of said strip material as said slots are formed therein.

[5. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said drive means comprise an hydraulic motor coupled to said roll shaft, a tachogenerator coupled to said roller shaft, a direct current electric motor coupled to said transport means, and an electrical circuit interconnecting the tacho-generator and the direct electric current motor.

16. Means according to claim 5 wherein said nonflexible material is metal. 

1. A method of forming longitudinally extending slots in a nonflexible strip material having a constant cross-sectional shape, the slotted strip material to be expanded by drawing edges thereof apart, comprising: driving the strip in the direction of its longitudinal axis and at right angles to the axis of a series of co-axial slotting rollers and through a cutting zone existing between the rollers and back-up means, each of said slotting rollers having at least one radial projection extending around it for part but not all of its circumference and terminating in curved surfaces which extend in radial directions, and simultaneously driving the slotting rollers rotationally to have their pitch cutting speed less than the speed of travel of the strip, thereby causing said projections to shear slugs from the strip material so as to form said slots in the strip material.
 2. A method of forming longitudinal slots in strip material according to claim 1 wherein said driving of the strip is effected by engaging one end of the strip with a dog on a transport chain, and driving the transport chain with an electric motor.
 3. A method of forming longitudinal slots in strip material according to claim 1 wherein said driving of the strip is effected by securing the strip to a table and driving the table with an electric motor.
 4. A method of forming longitudinal slots in strip material according to claim 2 wherein the electric motor is a variable speed direct current motor, and comprising controlling the speed of said motor by means of a tacho-generator coupled for drive to the slotting rollers and electrically coupled to said electric motor through a circuit which includes direct current feedback control means.
 5. Means for forming longitudinally extending slots in a non-flexible strip material having a constant cross-sectional shape, the slotted strip material to be expanded by drawing edges thereof apart, comprising a frame, a series of co-axial slotting rollers rotatably supported by the frame, each of said slotting rollers having at least one radial projection extending around it for part but not all of its circumference and terminating at its ends in curved surfaces which extend in radial directions, back-up means spaced from the rollers but being adjacent thereto so as to define with the rollers a cutting zone, transport means carried by the frame, drive means coupled to the rollers for rotational driving thereof, and further drive means coupled To the transport means for the driving thereof at a speed which exceeds the pitch cutting speed of the rollers, so constructed and arranged that a said strip of material when supported on the back-up means is driven by the transport means through the cutting zone while simultaneously the slotting rollers are driven rotationally, and said projections shear slugs from the strip so as to form slots.
 6. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said frame includes two pairs of upstanding slides, respective said bearings being guided for vertical movement between the slides of said pairs, and threaded members interconnecting the bearings and frame and constituting adjustment means for effecting adjustment of height of the bearings.
 7. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said back-up means comprise a back-up roller journalled in roller support bearings secured to the frame.
 8. Means for forming longitudinally extending slots in strip material according to claim 7 comprising further threaded members coupling the roller support bearings and the frame and constituting position adjustment means for the back-up roller for adjusting the position of the back-up roller in the direction of the longitudinal axis of the strip material.
 9. Means for forming longitudinally extending slots in strip material according to claim 7 wherein each of said back-up roller and said series of sliding rollers comprises a shaft, a shoulder at one end of the shaft, a series of annular spacers surrounding the shaft, clamping means clamping the annular spacers against the shoulder, and a tapered recess in each end of each respective said shaft.
 10. Means for forming longitudinally extending slots in strip material according to claim 5 further comprising an in-feed roll case carried by the frame and extending in one direction from the cutting zone, and an out-put roll case extending in the opposite direction therefrom.
 11. Means for forming longitudinally extending slots in strip material according to claim 10 further comprising height adjustment means between each said roll case and said frame.
 12. Means for forming longitudinally extending slots in strip material according to claim 10 further comprising a hold-down roller positioned above the out-feed roll case and adapted to bear against the upper surface of the workpiece at the out-feed side of said cutting zone.
 13. Means for forming longitudinally extending slots in strip material according to claim 5 wherein the slots of each said slotting roller radial projection decrease progressively in thickness radially inwardly from the periphery thereof to form a cutting clearance.
 14. Means for forming longitudinally extending slots in strip material according to claim 5 further comprising stripper plates between adjacent said slotting rollers, said stripper plates being positioned to bear against a surface of said strip material as said slots are formed therein.
 15. Means for forming longitudinally extending slots in strip material according to claim 5 wherein said drive means comprise an hydraulic motor coupled to said roll shaft, a tacho-generator coupled to said roller shaft, a direct current electric motor coupled to said transport means, and an electrical circuit interconnecting the tacho-generator and the direct electric current motor.
 16. Means according to claim 5 wherein said non-flexible material is metal. 